Check out example codes for "loading builder in flutter". It will help you in understanding the concepts better.

Code Example 1

Image(
  ...
  frameBuilder: (BuildContext context, Widget child, int frame, bool wasSynchronouslyLoaded) {
    return Padding(
      padding: EdgeInsets.all(8.0),
      child: child,
    );
  },
  loadingBuilder: (BuildContext context, Widget child, ImageChunkEvent loadingProgress) {
    return Center(child: child);
  },
)

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